Since the development of laser diodes, many applications for their use have been developed. Increasingly, laser diodes are employed for communications and are integral to optical disc recording and storage systems. Typically, edge emitting diode lasers are used. Edge emitting diode lasers, however, have a high cost in parallel and serial data links, and have a high current drain due to a high threshold current when used in compact disc pickups.
New systems are being developed to employ vertical cavity surface emitting lasers (VCSELs) in place of edge emitting lasers. The VCSELs provide a much lower cost, use surface emissions which simplify optical devices and are capable of being fabricated in larger volumes on semiconductor wafers. However, a problem exist in the packaging of such VCSELs, namely the cost of materials employed in the typical "can" type packages. The conventional semiconductor laser apparatus utilizes a metal TO can for packaging, and includes the formation of a "window" within a cap portion of the can through which the laser emission passes. In that metal is utilized in which a "window" must be formed, the cost of materials impacts the yield. Therefore, there exist a need for packaging of vertical cavity surface emitting lasers that would reduce the cost of manufacture.
In addition, there is a need to incorporate into the package a monitoring system which will automatically control the emissions emitted by the VCSEL. Generally, edge emitting laser diodes employ a power monitoring detector facing the back emission facet of the device. In a VCSEL with a wavelength shorter than 870 nm, there is no back emission due to the opaque substrate on which the device is necessarily formed.
Thus there is a need for a lower cost semiconductor laser package that has included therein a power monitoring system, thus allowing automatic power control (APC) of the VCSEL emission.
Accordingly, it is highly desirable and an object of this invention to provide for a low cost semiconductor laser package and method of fabrication that allows for monitoring of the VCSEL emission.
It is another purpose of the present invention to provide for a new and improved semiconductor laser package that is inexpensive, easily fabricated and allows for automatic power control of the VCSEL emission.
It is a still further purpose of the present invention to provide for a new and improved semiconductor laser package that is fabricated to include an optical element, such as a beam splitter, positioned to split a laser emission incident thereon, resulting in a small portion of the laser emission being reflected toward a power monitor and allowing a portion of the laser emission to pass therethrough.